It is proposed to identify and characterize the low-lying excited states of nucleic acid components via laser induced fluorescence (and its excitation spectrum) of supersonic molecular jets. We also propose to investigate the nature and the origin of ultrafast radiationless process from the excited singlet state of these species. Special attention will be paid to the possible connection between the photophysical behavior of DNA bases and the "proximity effect" in radiationless transitions of simpler N-Heterocyclic compounds.